1. Field of the Invention
The present invention relates to an image forming apparatus adapted to be optionally provided with an additional function such as a facsimile function besides a principal function as a copying machine and, more particularly, to means for readily providing the additional function to the apparatus for function expansion without a complicated modification work.
2. Description of Related Arts
In recent years, multi-function image forming apparatuses have been provided, which each have a plurality of functions to serve as a copying machine, a facsimile machine and a printer.
Some of the multi-function image forming apparatuses have a copying function as a principal function and are adapted to be optionally provided with an additional function such as a facsimile function. Such an image forming apparatus is preferably constructed so that the function expansion can be achieved in a simple and easy manner. More specifically, where the facsimile function is to be added to an image forming apparatus having the copying function as the principal function, the function expansion is preferably achieved by a simple setup operation by a user, which does not require a modification work on interconnections and circuit boards in the apparatus by a service person or an expert engineer.